1. Field of the Invention
The present invention relates to the art of mining and tunneling, and more particularly to a drill feed unit which provides increased penetration of a roof drill or the like into rock strata than existing feed units.
2. Description of the Prior Art
In the mining and tunneling industry, space to operate a drill is at a premium. Because of the lack of space in a mineshaft or tunnel, there is a need for a drill feed unit which is compact, but nevertheless can provide sufficient lift to the drill so as to allow maximum penetration of the drill into the roof, face or side wall of a mineshaft or tunnel. Accordingly, a drill feed unit which extends primarily upon a single longitudinal axis is highly desirable.
Most drill feed units in use today consist in part of mechanical linkage arrangements, which use sprockets and chains, for example, to extend the drill feed unit into the tunnel. Such arrangements are cumbersome, of great bulk and subject to frequent malfunctions because of the harsh and dirty environment in which mining drill feed units must operate. As a result, hydraulic systems have been proposed. Hydraulic lift systems can be constructed narrower and more compact than the bulky mechanical linkage systems. Despite the advantages offered by a hydraulic lift system, most drill feed units in operation remain, at least in part, composed of mechanical linkage lift arrangements.
One drawback with existing all-hydraulic drill feed units is that such systems are not adapted to extend exclusively along a single longitudinal axis. Rather, known hydraulic systems extend at least partially into the lateral direction to provide support to the unit. A further drawback of existing hydraulic systems is the use of eye-hook connectors between the piston rods of the hydraulic cylinders and the plates to which the rods are mounted. These eye-hook connectors take up much needed space when the hydraulic cylinders are in an unextended position and decrease the total extension possible for a drill feed unit of fixed height. Accordingly, there is a need for an all-hydraulic unit that extends primarily in a single longitudinal direction. Such a unit would be able to increase the penetration of the drill into the rock strata without increasing the height of the unextended unit.